bug#11218: with-demoted-errors use of condition-case-unless-debug; ert

[Glenn Morris]

Stefan Monnier wrote:

>> If you replace with-demoted-errors with ignore-errors, the test passes.
>
> Looks like a bug in ERT.

I don't know if it's a "bug" per se...

ert--run-test-internal binds debug-on-error to t, and redefines the
debugger to ert--run-test-debugger. As the doc of that function says:

  This function records failures and errors and either terminates the
  test silently or calls the interactive debugger, as appropriate.

(Whether or not the "real" debugger is invoked depends on the value of
ert-debug-on-error.)

So basically AFAICS it's an ert design choice that it works by borrowing
the debugger. I don't imagine it would be easy to change that.